Code No: R05310202
R05
Set No. 2
in
III B.Tech I Semester Examinations,November 2010 ELECTRICAL MEASUREMENTS Electrical And Electronics Engineering Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ????? 1. Explain the loss of charge method for measuring high resistance. Mention the possible errors and suggest methods to minimize these. [16]
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2. (a) Explain the advantages of instrument transformers as regards to extension of range of current and voltage on high voltage A.C. systems.
or
(b) A 1000/5A, 50Hz current transformer has a secondary burden comprising a non- inductive impedance of 1.6Ω.The primary winding has one turn. Calculate the flux in the core and ratio error at full load. Neglect leakage reactance and assume the iron loss in the core to be 1.5W at full load. [8+8] 3. (a) What are the errors in energy meter and how are the compensated in multielement induction type energy meter? How these energy meter errors will compare with that of watt-meter?
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(b) The disc of an energy meter makes 600 revolutions per unit energy. When a 1,000 watt load is connected, the disc rotates at 10.2 rpm, if the load is on for 12 hours, how many units are recorded as error? [10+6]
4. (a) Give the constructional details of electrodynamometer type wattmeter with a neat sketch.
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COSφ × Actual wattmeter reading for (b) Prove that the true power= COSφ.COS(φ−β) electrodynamometer type of wattmeters, where cosφ =p.f of the circuit, β = −1 wL tan where L and R are the inductance and resistance of the pressure R coil of the circuit. [8+8]
Aj
5. (a) Explain the method of measuring the dielectric loss of the capacitor at high voltage and high frequency. Derive the condition of balance for the bridge. Also, explain the precautions to be taken to ensure accuracy. Draw the phasor diagram under balance conditions. (b) In an Anderson bridge for measurement of inductance Lx and Resistance Rx in the arm AB, the arm CD and DA have resistances of 600 Ω each and the arm CE has a capacitor of 1µ F capacitor with A.C. supply at 100 Hz supplied across A and C, balance is obtained with a resistance of 400 Ω in arm DE and 800 Ω in the arm BC. Calculate the value of Lx and Rx . [10+6]
6. The cores of two identical transformers A and B carry alternating fluxes whose instantaneous values are (0.01 sin 314t)W and 0.012 (1.1 sin 628t+0.1 sin 1884t) W respectively. Find the ratio of eddy current loss of B to A. Find also the ratio of hysterisis loss of B to A. [16] 1
Code No: R05310202
R05
Set No. 2
7. (a) State the errors present in electrostatic instruments. (b) State the advantages and disadvantages of electrostatic instruments.
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(c) The capacitance of a 0-2,000 V electrostatic voltmeter increases uniformly from 42 to 54 pf from zero to full scale deflection. It is required to increase the range of the instrument to 20,000 V by means of an external capacitor. Calculate the value of capacitance required? [6+6+4]
Aj
nt
uW
or
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8. Explain the construction and working principle of a co-ordinate type A.C. potentiometer with the help of a neat diagram. [16]
2
Code No: R05310202
R05
Set No. 4
in
III B.Tech I Semester Examinations,November 2010 ELECTRICAL MEASUREMENTS Electrical And Electronics Engineering Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ????? 1. Explain the loss of charge method for measuring high resistance. Mention the possible errors and suggest methods to minimize these. [16]
ld .
2. (a) What are the errors in energy meter and how are the compensated in multielement induction type energy meter? How these energy meter errors will compare with that of watt-meter?
or
(b) The disc of an energy meter makes 600 revolutions per unit energy. When a 1,000 watt load is connected, the disc rotates at 10.2 rpm, if the load is on for 12 hours, how many units are recorded as error? [10+6] 3. (a) Explain the advantages of instrument transformers as regards to extension of range of current and voltage on high voltage A.C. systems.
uW
(b) A 1000/5A, 50Hz current transformer has a secondary burden comprising a non- inductive impedance of 1.6Ω.The primary winding has one turn. Calculate the flux in the core and ratio error at full load. Neglect leakage reactance and assume the iron loss in the core to be 1.5W at full load. [8+8] 4. (a) Explain the method of measuring the dielectric loss of the capacitor at high voltage and high frequency. Derive the condition of balance for the bridge. Also, explain the precautions to be taken to ensure accuracy. Draw the phasor diagram under balance conditions.
nt
(b) In an Anderson bridge for measurement of inductance Lx and Resistance Rx in the arm AB, the arm CD and DA have resistances of 600 Ω each and the arm CE has a capacitor of 1µ F capacitor with A.C. supply at 100 Hz supplied across A and C, balance is obtained with a resistance of 400 Ω in arm DE and 800 Ω in the arm BC. Calculate the value of Lx and Rx . [10+6]
Aj
5. (a) State the errors present in electrostatic instruments. (b) State the advantages and disadvantages of electrostatic instruments. (c) The capacitance of a 0-2,000 V electrostatic voltmeter increases uniformly from 42 to 54 pf from zero to full scale deflection. It is required to increase the range of the instrument to 20,000 V by means of an external capacitor. Calculate the value of capacitance required? [6+6+4]
6. The cores of two identical transformers A and B carry alternating fluxes whose instantaneous values are (0.01 sin 314t)W and 0.012 (1.1 sin 628t+0.1 sin 1884t) W respectively. Find the ratio of eddy current loss of B to A. Find also the ratio of hysterisis loss of B to A. [16] 3
Code No: R05310202
R05
Set No. 4
7. (a) Give the constructional details of electrodynamometer type wattmeter with a neat sketch.
in
COSφ (b) Prove that the true power= COSφ.COS(φ−β) × Actual wattmeter reading for electrodynamometer type of wattmeters, where cosφ =p.f of the circuit, β = −1 wL where L and R are the inductance and resistance of the pressure tan R coil of the circuit. [8+8]
8. Explain the construction and working principle of a co-ordinate type A.C. potentiometer with the help of a neat diagram. [16]
Aj
nt
uW
or
ld .
?????
4
Code No: R05310202
R05
Set No. 1
1. (a) State the errors present in electrostatic instruments.
in
III B.Tech I Semester Examinations,November 2010 ELECTRICAL MEASUREMENTS Electrical And Electronics Engineering Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ?????
(b) State the advantages and disadvantages of electrostatic instruments.
ld .
(c) The capacitance of a 0-2,000 V electrostatic voltmeter increases uniformly from 42 to 54 pf from zero to full scale deflection. It is required to increase the range of the instrument to 20,000 V by means of an external capacitor. Calculate the value of capacitance required? [6+6+4]
or
2. Explain the construction and working principle of a co-ordinate type A.C. potentiometer with the help of a neat diagram. [16]
uW
3. The cores of two identical transformers A and B carry alternating fluxes whose instantaneous values are (0.01 sin 314t)W and 0.012 (1.1 sin 628t+0.1 sin 1884t) W respectively. Find the ratio of eddy current loss of B to A. Find also the ratio of hysterisis loss of B to A. [16] 4. (a) Give the constructional details of electrodynamometer type wattmeter with a neat sketch. COSφ × Actual wattmeter reading for (b) Prove that the true power= COSφ.COS(φ−β) electrodynamometer type of wattmeters, where cosφ =p.f of the circuit, β = −1 wL tan where L and R are the inductance and resistance of the pressure R coil of the circuit. [8+8]
nt
5. (a) Explain the method of measuring the dielectric loss of the capacitor at high voltage and high frequency. Derive the condition of balance for the bridge. Also, explain the precautions to be taken to ensure accuracy. Draw the phasor diagram under balance conditions.
Aj
(b) In an Anderson bridge for measurement of inductance Lx and Resistance Rx in the arm AB, the arm CD and DA have resistances of 600 Ω each and the arm CE has a capacitor of 1µ F capacitor with A.C. supply at 100 Hz supplied across A and C, balance is obtained with a resistance of 400 Ω in arm DE and 800 Ω in the arm BC. Calculate the value of Lx and Rx . [10+6]
6. Explain the loss of charge method for measuring high resistance. Mention the possible errors and suggest methods to minimize these. [16] 7. (a) Explain the advantages of instrument transformers as regards to extension of range of current and voltage on high voltage A.C. systems.
5
Code No: R05310202
R05
Set No. 1
(b) A 1000/5A, 50Hz current transformer has a secondary burden comprising a non- inductive impedance of 1.6Ω.The primary winding has one turn. Calculate the flux in the core and ratio error at full load. Neglect leakage reactance and assume the iron loss in the core to be 1.5W at full load. [8+8]
in
8. (a) What are the errors in energy meter and how are the compensated in multielement induction type energy meter? How these energy meter errors will compare with that of watt-meter?
Aj
nt
uW
or
?????
ld .
(b) The disc of an energy meter makes 600 revolutions per unit energy. When a 1,000 watt load is connected, the disc rotates at 10.2 rpm, if the load is on for 12 hours, how many units are recorded as error? [10+6]
6
Code No: R05310202
R05
Set No. 3
in
III B.Tech I Semester Examinations,November 2010 ELECTRICAL MEASUREMENTS Electrical And Electronics Engineering Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ?????
ld .
1. (a) Explain the method of measuring the dielectric loss of the capacitor at high voltage and high frequency. Derive the condition of balance for the bridge. Also, explain the precautions to be taken to ensure accuracy. Draw the phasor diagram under balance conditions.
or
(b) In an Anderson bridge for measurement of inductance Lx and Resistance Rx in the arm AB, the arm CD and DA have resistances of 600 Ω each and the arm CE has a capacitor of 1µ F capacitor with A.C. supply at 100 Hz supplied across A and C, balance is obtained with a resistance of 400 Ω in arm DE and 800 Ω in the arm BC. Calculate the value of Lx and Rx . [10+6] 2. Explain the construction and working principle of a co-ordinate type A.C. potentiometer with the help of a neat diagram. [16]
uW
3. (a) Give the constructional details of electrodynamometer type wattmeter with a neat sketch. COSφ × Actual wattmeter reading for (b) Prove that the true power= COSφ.COS(φ−β) electrodynamometer type of wattmeters, where cosφ =p.f of the circuit, β = tan−1 wL where L and R are the inductance and resistance of the pressure R coil of the circuit. [8+8]
4. (a) Explain the advantages of instrument transformers as regards to extension of range of current and voltage on high voltage A.C. systems.
nt
(b) A 1000/5A, 50Hz current transformer has a secondary burden comprising a non- inductive impedance of 1.6Ω.The primary winding has one turn. Calculate the flux in the core and ratio error at full load. Neglect leakage reactance and assume the iron loss in the core to be 1.5W at full load. [8+8]
Aj
5. (a) State the errors present in electrostatic instruments. (b) State the advantages and disadvantages of electrostatic instruments. (c) The capacitance of a 0-2,000 V electrostatic voltmeter increases uniformly from 42 to 54 pf from zero to full scale deflection. It is required to increase the range of the instrument to 20,000 V by means of an external capacitor. Calculate the value of capacitance required? [6+6+4]
6. (a) What are the errors in energy meter and how are the compensated in multielement induction type energy meter? How these energy meter errors will compare with that of watt-meter? 7
Code No: R05310202
R05
Set No. 3
(b) The disc of an energy meter makes 600 revolutions per unit energy. When a 1,000 watt load is connected, the disc rotates at 10.2 rpm, if the load is on for 12 hours, how many units are recorded as error? [10+6] 7. Explain the loss of charge method for measuring high resistance. Mention the possible errors and suggest methods to minimize these. [16]
Aj
nt
uW
or
?????
ld .
in
8. The cores of two identical transformers A and B carry alternating fluxes whose instantaneous values are (0.01 sin 314t)W and 0.012 (1.1 sin 628t+0.1 sin 1884t) W respectively. Find the ratio of eddy current loss of B to A. Find also the ratio of hysterisis loss of B to A. [16]
8
